There has been known an image forming apparatus which includes a photosensitive drum configured to form an electrostatic latent image thereon, a charging roller configured to contact the photosensitive drum and charge the photosensitive drum, and a developing device configured to supply toner to an electrostatic latent image on the photosensitive drum to form a toner image on the photosensitive drum (refer to JP-A-2003-280334). In this image forming apparatus, when toner attached on the charging roller reaches a predetermined amount, a collection control of discharging the toner on the charging roller to the photosensitive drum and collecting the toner into the developing device via the photosensitive drum is executed.
However, in this information forming apparatus, the collection control is not performed as long as the amount of the toner attached on the charging roller is less than the predetermined amount. Therefore, the toner may be held on the charging roller for a long time. In this case, since the charge amount of the toner on the charging roller is gradually decreased and a holding force of the toner by the charging roller is gradually lowered, the toner may be detached from the charging roller and the detached toner may cause a printing defect.